Presidential confidant Bruce R. Lindsey returned to the grand jury investigating the Monica S. Lewinsky matter yesterday for his third day of testimony -- an appearance that may help set the stage for a constitutional battle over President Clinton's ability to protect the secrecy of his discussions with advisers.

Lindsey, a White House deputy counsel and longtime Clinton friend from Arkansas, has played an important role at several points in the Lewinsky saga and has declined to answer questions at the grand jury about his conversations with the president. Lawyers are compiling a record of which matters Lindsey considers confidential in preparation for a court fight over the reach of Clinton's executive privilege.

As he departed from the courthouse after about 2 1/2 hours before the grand jury, Lindsey would not discuss his testimony or whether the privilege issue came up. "You know we aren't talking about that," he told reporters.

The grand jury yesterday also heard again from White House steward Bayani Nelvis, who works in the pantry adjacent to the Oval Office and befriended Lewinsky when she worked at the White House as an intern and later as a correspondence clerk. And while testimony continued on one floor, the federal judge who oversees the grand jury, Norma Holloway Johnson, heard arguments on another about Clinton's complaint that independent counsel Kenneth W. Starr's office has illegally leaked grand jury information to the news media.

Starr has shown special interest in both Lindsey and Nelvis, the only witnesses to be summoned three times before the grand jury. Their return suggested that prosecutors may have wanted to ask questions based on testimony obtained from other witnesses since their earlier sessions, such as Kathleen E. Willey, who testified this week about her allegations that Clinton made an unwanted sexual advance to her when she came to him seeking a job.

Lindsey has been the most visible, and most knowledgeable, Clinton adviser entangled in the dispute over what information might be covered by executive privilege, but two other aides are also involved -- White House adviser Sidney Blumenthal, who declined to answer some questions during his testimony, and deputy chief of staff John D. Podesta, who has testified once and is set to return to the grand jury March 24.

Only Clinton can formally invoke executive privilege and, while the issue is under court seal, lawyers involved have said they do not believe he has done so yet while the scope of the dispute is being defined by the questions that are rebuffed.

Unlike Lindsey's last appearance, when he came with a squadron of lawyers from the Clinton team, he arrived at the courthouse yesterday with only fellow White House deputy counsel Cheryl D. Mills and his personal attorney, William Murphy. "He will not be back next week," Murphy said afterward. "He seems to be done -- for the time being."

Lindsey has been the White House adviser most involved in seeking to minimize political damage from allegations of womanizing by the president. In his deposition in the Paula Jones case, Clinton said Lindsey was the one who informed him that Lewinsky was on the witness list. The list was turned over to Clinton's attorneys on Dec. 5, but it was not clear in the president's deposition when Lindsey told him Lewinsky was on it.

The timing could be significant, because Starr is investigating what prompted Clinton friend Vernon E. Jordan Jr. to help find Lewinsky a job. Jordan has told associates his efforts began Dec. 8, after he was asked by Clinton's personal secretary, Betty Currie. Starr is trying to learn whether the job help was intended to keep Lewinsky quiet about an alleged sexual relationship with Clinton.

Lindsey also may have been questioned yesterday about his conversations with Linda R. Tripp last summer about Willey, a former White House aide who purportedly told Tripp, a White House colleague of Willey's, that she was kissed and groped by Clinton in a hallway connecting the Oval Office with the pantry where Nelvis works. Willey appears to be cooperating closely with Starr's investigation.

Tripp consulted with Lindsey about the matter when she was contacted by Newsweek last summer, according to a source close to Tripp. In the resulting article, Tripp said Willey did not appear to have been sexually harassed by the president but rather seemed happy when recounting the incident.

Nelvis testified during the grand jury's morning session and his attorney, Joseph T. Small Jr., declined to comment as they left the courthouse. Nelvis testified on the first day of grand jury proceedings in the Lewinsky case Jan. 27 and then was brought back a week later. Because of his proximity to the Oval Office, Nelvis had access to see many of the comings and goings.

In a separate hearing, Clinton lawyer David E. Kendall argued that the independent counsel should have to prove he should not be held in contempt of court for purported grand jury leaks. Starr personally attending the hearing, as did Lewinsky's lawyers, William H. Ginsburg and Nathaniel H. Speights.

Judge Johnson kept the hearing closed, rejecting a request to allow in reporters made by attorney Theodore Boutrous, representing news organizations including The Washington Post. Boutrous had filed a request to open the hearing to the public and said he made sure copies were given to all parties.

But because Starr's office, Kendall and Ginsburg all said they had not had a chance to respond to the media's motion, Johnson said it would be "premature" for her to rule on it, Boutrous said. After Johnson refused to allow Boutrous to argue the point, he said he was "escorted from the courtroom."